1. Technical Field
This patent application relates, in general, to suppressing electromagnetic radiation in and around printed circuit boards.
2. Description of the Related Art
Printed circuit boards used in various types of data processing systems (e.g., computers) are typically mounted within a plastic or sheet metal housing structure. During operation of a printed circuit board electromagnetic radiation is generated.
Electromagnetic radiation can interfere with data processing system operation. Accordingly, efforts are made within the art to shield printed circuit boards and printed circuit board components from electromagnetic radiation. Conventionally, such shielding is accomplished via a sheet metal housing (often referred to in the art as a xe2x80x9ccanxe2x80x9d or xe2x80x9cfencexe2x80x9d) used to enclose a printed circuit board. The sheet metal housing is normally grounded directly to a ground plane in the printed circuit board.
Printed circuit boards are conventionally referred to as motherboards and daughterboards. A motherboard is the main circuit board containing the primary components of a computer system. A daughterboard is a circuit board that attaches to a motherboard, or other type board, and provide additional or enhanced functions to a motherboard.
A daughterboard is typically connected to a motherboard via a card edge connector, the socket portion of which is conductively mounted on the motherboard, and the pin portion of which is an edge of the daughterboard with conductive traces thereon. Conventionally, the motherboard is generally horizontally disposed in the bottom portion of the housing structure, and the daughterboard is generally vertically disposed, being connected at its bottom edge to the card edge connector on the top surface of the motherboard. Daughterboards are also typically shielded with metal fences, or cans, in a fashion analogous to that described for motherboards.
Recent advances in the art have resulted in a movement toward smaller and smaller enclosures for the printed circuit boards used in data processing systems. Accordingly, it is becoming common for daughterboards to be oriented parallel with the motherboard, so that the necessary height requirement for the system is decreased. However, even with the daughterboards so oriented, the conventional method of shielding the mother and daughterboards and their attendant components continues to be a can, or fence, enclosing the area to be shielded.
Such a manner of shielding is disadvantageous for several reasons. For example, it is difficult to orient and correctly place the fence during board fabrication. The presence of the fence also creates a heat dissipation problem. In addition, the presence of the can requires the use of secondary parts and equipment above and beyond that normally necessary to fabricate printed circuit boards. Furthermore, use of the fence or can is generally fairly inflexible in that ordinarily it is used to enclose the entire board surface to be shielded.
From the foregoing, it is therefore apparent that a need exists in the art for a device which provides shielding of printed circuit boards from electromagnetic radiation in a way that overcomes or alleviates the foregoing noted disadvantages.
A device and a method of manufacturing the device have been discovered which provide shielding of printed circuit boards and printed circuit board components such that entire printed circuit boards and/or individual printed circuit board components can be shielded, the extra manufacturing steps and equipment associated with conventional devices for shielding printed circuit boards can be substantially eliminated, heat dissipation is increased over conventional devices for shielding printed circuit boards, and shielding can be implemented with standard printed circuit board manufacturing technology. In one embodiment a device includes a printed circuit board, and at least two electrical connectors proximate to the printed circuit board, with the at least two electrical connectors spaced to attenuate at least one prespecified frequency electromagnetic energy waveform. In another embodiment a data processing system includes at least one microprocessor mounted on at least one printed circuit board, and at least two electrical connectors proximate to the printed circuit board, with the at least two electrical connectors spaced to attenuate at least one prespecified frequency electromagnetic energy waveform. In yet another embodiment, a method of manufacturing includes deploying at least two electrical connectors proximate to a printed circuit board, said at least two electrical connectors spaced to attenuate at least one prespecified frequency electromagnetic energy waveform.
The foregoing is a summary and thus contains, by necessity, simplifications, generalizations and omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of this patent application will become apparent in the non-limiting detailed description set forth below.